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Far-Field Impacts of Tidal Energy Extraction and Sea Level Rise in the Gulf of Maine

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University of Rhode Island DigitalCommons@URI Open Access Master's Theses 2016 Far-Field Impacts of Tidal Energy Extraction and Sea Level Rise in the Gulf of Maine Boma Kresning University of Rhode Island, [email protected] Follow this and additional works at: https://digitalcommons.uri.edu/theses Recommended Citation Kresning, Boma, "Far-Field Impacts of Tidal Energy Extraction and Sea Level Rise in the Gulf of Maine" (2016). Open Access Master's Theses. Paper 903. https://digitalcommons.uri.edu/theses/903 This Thesis is brought to you for free and open access by DigitalCommons@URI. It has been accepted for inclusion in Open Access Master's Theses by an authorized administrator of DigitalCommons@URI. For more information, please contact [email protected]. FAR-FIELD IMPACTS OF TIDAL ENERGY EXTRACTION AND SEA LEVEL RISE IN THE GULF OF MAINE BY BOMA KRESNING A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN OCEAN ENGINEERING UNIVERSITY OF RHODE ISLAND 2016 MASTER OF SCIENCE THESIS OF BOMA KRESNING APPROVED: Thesis Committee: Major Professor M. Reza Hashemi Jason Dahl John W. King Nasser H. Zawia DEAN OF THE GRADUATE SCHOOL UNIVERSITY OF RHODE ISLAND 2016 ABSTRACT The dynamics of tides in the Gulf of Maine are unique due to the tidal reso- nance, which generates the largest tidal range in the world (about 16 m). Conse- quently, a large tidal energy resource is available in this area, particularly in the Bay of Fundy, and is expected to be harvested in the future. Currently, more than 6 projects are operational or under development in this region (in both US and Canadian waters). Understanding the far-field impacts of tidal-stream arrays is important for future development of tidal energy extraction. The impacts include possible changes in water elevation, currents, and sediment transport. Accord- ingly, a number of previous studies have assessed the impacts of the tidal energy development in the Gulf of Maine. Further, due to the sea level rise (SLR), those impacts may also change during the project lifetime, which is usually more than 25 years. The objective of this study is to assess the combined effects of SLR and tidal energy extraction on the dynamics of tides in the Gulf of Maine. A tidal model of the Gulf of Maine was developed using Regional Ocean Model System (ROMS) at one arcminute scale. The model extends from 71.5W to 63.0W and from 39.5N to 46.0N. After validation of the model at NOAA tidal gauge stations and NERACOOS buoys, several scenarios; including SLR scenario, and tidal extraction scenario, were examined. Recent studies suggest that the global dynamics of tides will change due to SLR; therefore, SLR not only affects the bathymetry of the model inside the domain, it also changes the boundary forcing, which was considered in this effort. The results of the impacts of the tidal energy extraction with and without the SLR were presented, and compared with those from literature. Up to 4% decrease in tidal range and M2 amplitude was estimated in Minas Basin due to the 2.5 GW extraction scenario without SLR. On Massachusetts coastal area, the impacts of the same scenario can be considered negligible, 0.94%. In summary, the implementation of modified boundary forcing due to SLR, which was ignored in the previous works, can change the results of the impact assessment. Based on the results, the far-field impact is more threatening in coastal regions of US. However, the impact of energy extraction in Minas Passage is relatively small. Compared to the model validation, the impacts were inside the uncertainty level of the model. For example, maximum change in Boston coastal area was calculated up to 1.65 %, which is inside the level of uncertainty in models, about 10 %. Furthermore, the impact of SLR on the dynamics of tides is much more than energy extraction assuming 2.5 GW extraction in Minas Passage. ACKNOWLEDGMENTS First, I would like to acknowledge my Major Professor, M. Reza Hashemi for his continuous support, guidance, and help of this thesis. Also, I want to appreciate my other committee members, Jason Dahl, John King, Malcolm Spaulding and Huijie Xue for their input in my thesis. Additionally, a thank you for Matias Green and Sophie B. Williams from Bangor University, Wales for their support in global change in tidal dynamics data for this thesis. Lastly, I would like to acknowledge my colleagues in ocean engineering URI, Michael Shelby and Lauren Schambach for their assistance. Thank you for a great time in Ocean Engineering URI. iv TABLE OF CONTENTS ABSTRACT .................................. ii ACKNOWLEDGMENTS .......................... iv TABLE OF CONTENTS ..........................v LIST OF TABLES ............................... viii LIST OF FIGURES ..............................x CHAPTER 1 Introduction ...............................1 1.1 Background . .1 1.2 Area of study . .1 1.3 Literature review . .2 1.3.1 Tidal energy development . .2 1.3.2 Tidal energy resource in the Gulf of Maine . .6 1.3.3 Physical impacts of tidal energy extraction . .7 1.3.4 Sea level rise . 10 1.3.5 Introductory remarks . 12 1.4 Objectives . 14 2 Methods ................................. 16 2.1 Data . 16 2.1.1 Bathymetry . 16 2.1.2 TPXO7 . 16 v Page 2.1.3 Tidal water elevation and tidal amplitude . 16 2.1.4 Tidal current velocity data . 17 2.1.5 SLR . 17 2.2 Methodology . 18 2.3 Theoretical background . 18 2.3.1 Tidal constituents . 18 2.3.2 Resonance in a basin . 18 2.3.3 Empirical equations for vertical velocity profile . 20 2.3.4 Simulations of tidal turbine in ocean models . 20 2.4 Tidal modeling using ROMS . 22 2.4.1 ROMS theoretical background . 22 2.4.2 Bottom stress parameterization . 22 2.5 Tidal turbines simulation in ROMS model . 24 2.5.1 Increasing bottom friction to simulate energy extraction . 24 2.5.2 Actuator disc concept . 25 2.6 ROMS tidal model development . 26 2.6.1 Tidal stream resource assesment . 27 2.6.2 Impact of tidal stream turbines and SLR . 28 3 Results .................................. 29 3.1 Model validation . 29 3.1.1 Tidal amplitudes validation . 29 3.1.2 Tidal current validation . 34 3.1.3 Increased bottom drag coefficient and tidal energy ex- traction . 40 vi Page 3.2 Tidal resource assessment in the Gulf of Maine . 42 3.2.1 Present tidal energy resources in the Gulf of Maine . 43 3.2.2 Impacts of SLR on the tidal stream energy resource . 45 3.3 Impacts of energy extraction and SLR on tidal dynamics . 46 4 Discussion ................................ 56 5 Conclusion ................................ 59 LIST OF REFERENCES .......................... 61 BIBLIOGRAPHY ............................... 64 vii LIST OF TABLES Table Page 1.1 Some of the tidal barrage/lagoon projects worldwide (Multon, 2013) . .3 1.2 Some important tidal-stream projects in the world (Bahaj, 2011)3 1.3 Tidal energy sites (mostly under study) in the Gulf of Maine. .7 2.1 10 Significant Tidal Constituents . 19 2.2 List of Symbols in ROMS Formulation . 23 2.3 List of variables for turbine simulation in ROMS model. 25 3.1 Comparison of M2 constituents at 11 tidal stations . 31 3.2 Comparison of S2 constituents at 5 tidal stations . 32 3.3 Tidal ellipse parameters comparison between ROMS and ob- served data. 37 3.4 Tidal energy extraction scenario summary . 41 3.5 Power flux calculation summary at Minas Passage for 1.23 GW tidal-stream extraction scenario . 43 3.6 Summary of available maximum theoretical power at Minas Pas- sage and comparison with the previous studies. 44 3.7 Summary of available maximum theoretical power in the Gulf of Maine (see Figure 3.14 for site locations). 45 3.8 Summary of available average theoretical power and the impacts on the resources in the Gulf of Maine (see Figure 3.14 for site locations). 47 3.9 Summary of energy extraction scenarios in ROMS. 48 viii Table Page 3.10 Impact of energy extraction and SLR scenarios on the M2 am- plitude at Minas Basin and Boston. The M2 amplitudes at the present day are 5.24 m and 1.49 m for Minas Basin and Boston, respectively. 49 3.11 Impact of energy extraction and SLR scenarios on the tidal range at Minas Basin and Boston. The tidal range at the present day are 15.08 m and 4.54 m for Minas Basin and Boston, respec- tively. 50 3.12 Summary of the model validation from research related to the impacts of tidal-stream energy extraction in the Gulf of Maine. 50 5.1 Summary of the impact of energy extraction and SLR scenarios on the M2 and the tidal range. The tidal range at the present day are 15.08 m and 4.54 m for Minas Basin and Boston, respec- tively. For the M2 component, the amplitudes at the present day are 5.24 m and 1.49 m for Minas Basin and Boston, respectively. 60 ix LIST OF FIGURES Figure Page 1.1 Map of the Gulf of Maine including the bathymetry. Red stars show tidal stations for sea level data, red triangles show NER- ACOOS buoys and numbers show previously studied sites. See Table 1.3 for list of projects. .2 1.2 Illustration of stream turbine types (Khan et al., 2009). .4 1.3 Power curve for the SeaGen-S tidal stream turbine by Marine Current Turbine. .4 1.4 Illustration of tidal-stream turbine arrays (Divett et al., 2013; Chowdhury et al., 2013). .5 1.5 Optimum multiple line array configuration with recommended spacing between turbines. Colors represents generated wake from the turbines due to incoming current.
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